A large body of research has established that there is a strong association between excessive alcohol consumption and numerous adverse health and social outcomes, but there is less evidence as to what proportion of this correlation is causal. This project will estimate the effect of alcohol consumption on the probability of arrest, hospitalization, and death by exploiting the fact that an individual's access to alcohol increases discretely at age 21 the minimum legal drinking age in the US. This institutional feature allows the use of a regression discontinuity design (RDD) to obtain unbiased estimates of the effect of alcohol consumption on the rate of adverse outcomes. The RDD approach takes advantage of a situation in which the treatment of interest varies discontinuously across some predetermined threshold (e.g. a discontinuous change in alcohol availability upon turning age 21). In this case, comparisons of individuals just on either side of the threshold will yield an unbiased estimate of the true effect of the treatment on outcomes since -- apart from the treatment of interest -- all other variables will trend smoothly across the discontinuity. This research will implement a series of RDD analyses using both survey and confidential administrative data on alcohol consumption, arrests, hospitalizations and deaths to identify the reduced form causal effects of minimum drinking age laws on alcohol consumption and its adverse outcomes. The first step will be documenting how both the frequency and intensity of alcohol consumption change at age 21. The next step will be to determine which types of injuries, causes of death, and types of crimes are causing any abrupt increases in adverse events and how this varies by race and ethnicity. Combining the reduced form estimates will give the implied Instrumental Variables estimate of the return to reducing alcohol consumption. The overall goal of this research project is to provide estimates of the returns to reducing alcohol consumption that policymakers can use when they are considering policies intended to reduce the adverse effects of alcohol consumption. The credible research design and the fact that the study focuses on a broad array of the adverse effects of alcohol consumption among youth mean it is well suited to accomplishing this important goal. Relevance This research project will evaluate the degree to which the minimum legal drinking age in the United States reduces alcohol consumption, mortality, injury, and crime among young adults. Since underage drinking rates in the US remain at startlingly high levels, our results will have important implications for the design of public health policies that would limit the availability of alcohol to youths. In so doing, this project will have the potential to reduce alcohol related harms experienced by youths.